JP2007127591A - Optical sensor controller and optical sensor control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem wherein erroneous detection occurs as to the presence of an object, when the photoreception sensitivity of a photoreception part and the brightness of a light emitting part are dispersed caused by a dispersion in production, in a plurality of optical sensors, or when the photoreception sensitivity of the photoreception part and the brightness of the light emitting part get low caused by deterioration along with the lapse of time, in any of the optical sensors. <P>SOLUTION: An optical sensor controller for controlling the optical sensor has the light emitting part and the photoreception part for outputting a voltage in response to a photoreception quantity so as to detect the presence of the inspecting object. The controller includes a reading part for reading an output voltage value of the voltage output from the photoreception part, and a regulation part capable of regulating the photoreception sensitivity of the photoreception part. The reading part reads the output voltage value under the prescribed condition where the photoreception quantity in the photoreception part of light emitted from the light emitting part gets maximum, in a detection position determined by an installation position of the light emitting part and an installation position of the photoreception part. The regulation part regulates the photoreception sensitivity, based on the read output voltage value read under the prescribed condition, by the reading part. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a control technique for an optical sensor, and more particularly to a technique for suppressing erroneous detection when detecting the presence or absence of an object using an optical sensor.

  Conventionally, in order to detect the presence or absence of an object, an optical sensor having a light emitting part and a light receiving part has been widely used. In this optical sensor, the light receiving unit outputs a voltage having a magnitude corresponding to the amount of received light. Therefore, the presence or absence of an object can be detected by reading the output voltage value at the light receiving unit and determining whether or not the output voltage value has reached a preset threshold voltage value.

  Specifically, for example, in an optical sensor called a so-called transmissive photo interrupter, a light emitting unit and a light receiving unit are arranged apart from each other by a predetermined distance (hereinafter referred to as “detection gap”). And if an object exists in this detection gap, the light inject | emitted from a light emission part will be interrupted | blocked by this object. As a result, the amount of light received by the light receiving portion is reduced, and the output voltage value does not reach a preset threshold voltage value. In this case, it can be detected that there is an object.

  As described above, an optical sensor described in Patent Document 1 described below is an example of an optical sensor that includes a light emitting unit and a light receiving unit and is used for detecting the presence or absence of an object.

JP 2000-131140 A

  The light receiving sensitivity of the light receiving unit of the optical sensor may be reduced due to the deterioration of the light receiving unit over time. Then, due to the decrease in the light receiving sensitivity, the correspondence (output voltage characteristics) between the amount of received light and the output voltage value changes in the light receiving unit. As a result of the change in the output voltage characteristic, erroneous detection of the presence or absence of an object may occur.

  For example, when the optical sensor is the above-described transmissive photointerrupter, if the light receiving sensitivity of the light receiving unit decreases due to deterioration with time, the output voltage value becomes lower than before shipment even with the same amount of received light. As a result, although there is no object in the detection gap, the output voltage value does not reach the threshold voltage value, and it may be erroneously detected that there is an object.

  Such erroneous detection can also occur due to deterioration with time of the light emitting unit. In other words, the luminance of the light emitting unit has decreased compared to before shipping due to deterioration over time, so the amount of light received at the light receiving unit is reduced, and as a result, the output voltage value does not reach the threshold voltage value, and there is no object in the detection gap. Nevertheless, if there is an object, it may happen that it is erroneously detected.

  On the other hand, the light receiving sensitivity of the light receiving unit and the luminance of the light emitting unit may be different for each of the plurality of optical sensors due to manufacturing variations. In such a case, when the same threshold voltage value is set for a plurality of photosensors, the output voltage value when there is no object in the detection gap in some of the photosensors is the threshold voltage value. The detection voltage may be falsely detected when there is an object, or the output voltage value when the object is in the detection gap exceeds the threshold voltage value and may be erroneously detected when there is no object.

  Therefore, for each optical sensor, measure the output voltage value when there is no object in the detection gap and the output voltage value when there is an object in the detection gap, and prevent false detection based on the measured output voltage value. It was very troublesome to set an appropriate threshold voltage value.

  Note that the above-described problem can occur not only in a transmissive photointerrupter but also in a so-called reflective photointerrupter. Here, the reflection type photo interrupter is an optical sensor that has a light emitting part and a light receiving part, and receives light reflected by the light receiving part when the light emitted from the light emitting part is reflected by an object to be detected. is there. Therefore, when an object is present, the amount of light received by the light receiving unit is greater than when no object is present.

  The present invention has been made to solve at least a part of the problems described above, and in a plurality of optical sensors, there is a variation in light receiving sensitivity of the light receiving unit and luminance of the light emitting unit due to manufacturing variations. Another object of the present invention is to suppress erroneous detection of the presence or absence of an object by a simple method when the light receiving sensitivity of the light receiving unit and the luminance of the light emitting unit are reduced due to deterioration over time. .

  In order to solve at least a part of the aforementioned problems, an optical sensor control device of the present invention has a light emitting unit and a light receiving unit that outputs a voltage corresponding to the amount of received light, and detects the presence or absence of a detection target. An optical sensor control device for controlling an optical sensor for reading, a reading unit for reading an output voltage value of a voltage output from the light receiving unit, and a light receiving sensitivity of the light receiving unit can be adjusted An adjustment unit, and the reading unit has a light receiving amount of light emitted from the light emitting unit at a detection position determined by an installation position of the light emitting unit and an installation position of the light receiving unit. The output voltage value is read under a maximum predetermined condition, and the adjustment unit adjusts the light receiving sensitivity based on the read output voltage value read by the reading unit under the predetermined condition. To do.

  Thus, in the optical sensor control device of the present invention, the adjustment unit reads the reading read by the reading unit under a predetermined condition in which the amount of light emitted from the light emitting unit at the light receiving unit is maximized at the detection position. The light receiving sensitivity is adjusted based on the output voltage value. Here, when the light receiving sensitivity of the light receiving unit decreases due to deterioration over time, the output voltage value decreases even if the amount of light received by the light receiving unit does not change, and the reading unit reads a lower output voltage value. When the reading unit reads a lower output voltage value, if the adjustment unit adjusts to increase the light receiving sensitivity, the output voltage value increases. False detection can be suppressed. Also, when the luminance of the light emitting unit decreases due to deterioration over time, the amount of light received at the light receiving unit decreases, and thus the output voltage value decreases. In this case as well, the output voltage value decreases. It is possible to suppress erroneous detection of the presence or absence of the detection target.

  Further, when the light receiving sensitivity of the light receiving unit is relatively low due to manufacturing variations, or when the luminance of the light emitting unit is relatively low, the reading unit reads a relatively low output voltage value. Then, when the reading unit reads a relatively low output voltage value, if the adjustment unit adjusts so as to increase the light receiving sensitivity, the output voltage value increases, so that the output voltage value is relatively low. The erroneous detection about the presence or absence of the detection target to accompany can be suppressed.

  Furthermore, by setting it as said structure, when the said optical sensor is manufactured in multiple numbers, about each optical sensor, the output voltage value when there exists a detection target object, or the output voltage value when there is no detection target object In addition to measuring in advance, there is no need to set an appropriate threshold voltage value that will not cause false detection of the presence or absence of the detection target based on the measured output voltage value. can do.

  In the optical sensor control device, the adjustment unit compares the read output voltage value with an upper limit value and a lower limit value of a preset ideal output voltage value range, and the adjustment unit includes the read output voltage value. It is preferable that when the value is higher than the upper limit value, the light reception sensitivity is decreased, and when the reading output voltage value is lower than the lower limit value, the light reception sensitivity is increased.

  In this way, when the light receiving sensitivity of the light receiving unit or the luminance of the light emitting unit is decreased, or when the light receiving sensitivity of the light receiving unit or the luminance of the light emitting unit is relatively low due to manufacturing variation, the read output voltage value is decreased. However, if the value is lower than the lower limit value, the light receiving sensitivity increases, so that the read output voltage value also increases. In addition, due to manufacturing variations, when the light receiving sensitivity of the light receiving unit or the luminance of the light emitting unit is relatively high, the read output voltage value is relatively high, but when it is higher than the upper limit value, the light receiving sensitivity is decreased. Therefore, the read output voltage value also decreases. Therefore, the read output voltage value falls within the ideal output voltage range, and erroneous detection of the presence or absence of the detection target can be suppressed.

  In the optical sensor control device, the light receiving unit includes a phototransistor, the adjustment unit includes a load resistor connected to the phototransistor, and the adjustment unit includes the read output voltage value of the upper limit value. If the output voltage value is lower than the lower limit value, the resistance value of the load resistance is changed to a larger value. May be.

  In this way, when the read output voltage value is higher than the upper limit value, the resistance value of the load resistance connected to the phototransistor is changed to a smaller value, so that the light receiving sensitivity of the light receiving unit can be lowered. it can. Further, when the read output voltage value is lower than the lower limit value, the resistance value of the load resistor connected to the phototransistor is changed to a larger value, so that the light receiving sensitivity of the light receiving unit can be increased.

  In the optical sensor control device, the optical sensor is a transmissive photo interrupter, and the predetermined condition is a condition that there is no detection target in a gap between the light emitting unit and the light receiving unit. You may do it.

  By doing so, the light receiving sensitivity of the light receiving unit decreases, and as a result, when the output voltage value at the same light receiving amount decreases, there is no detection target in the gap between the light emitting unit and the light receiving unit. Nevertheless, erroneous detection when there is a detection object can be suppressed. Similarly, when the luminance of the light emitting unit decreases and as a result, the output voltage value decreases, there is a detection target even though there is no detection target in the gap between the light emitting unit and the light receiving unit. Erroneous detection can be suppressed.

  In addition, due to manufacturing variations, when the light receiving sensitivity of the light receiving unit is relatively low, or when the luminance of the light emitting unit is relatively low, there is no detection target in the gap between the light emitting unit and the light receiving unit. It is possible to suppress erroneous detection when there is a detection object.

  In addition, due to manufacturing variations, when the light receiving sensitivity of the light receiving unit is relatively high, or when the luminance of the light emitting unit is relatively high, there is a detection target in the gap between the light emitting unit and the light receiving unit. It is possible to suppress erroneous detection when there is no detection target.

  The present invention is not limited to the device invention aspect such as the above-described optical sensor control apparatus, and can also be realized as a method invention such as an optical sensor control method.

Hereinafter, the best mode for carrying out the present invention will be described in the following order based on examples.
A. Example:
A1. Outline configuration of optical sensor and optical sensor control device:
A2. Overview of light sensitivity adjustment processing:
A3. Details of light sensitivity adjustment processing:
A4. Effects of the embodiment:
B. Variation:

A. Example:
A1. Outline configuration of optical sensor and optical sensor control device:
FIG. 1 is an explanatory diagram showing a schematic configuration of an optical sensor and an optical sensor control device as an embodiment of the present invention.

  An optical sensor 100 shown in FIG. 1 mainly includes a light emitting unit 110 having a light emitting diode 111 and a light receiving unit 120 having a phototransistor 121.

  The light emitting diode 111 emits light, and the phototransistor 121 is turned on by receiving the light emitted from the light emitting diode 111, and a voltage corresponding to the amount of received light is output to the terminal P1.

  Here, the optical sensor 100 is a transmissive photo interrupter, and the light emitting unit 110 and the light receiving unit 120 described above are arranged apart from each other by a detection gap G1, and the terminal P1 depends on whether or not there is an object in the detection gap G1. The output voltage at will change.

  Specifically, when there is an object in the detection gap G1, the light emitted from the light emitting diode 111 is reflected by the object, so that the amount of light received by the phototransistor 121 is relatively small, and as a result, the terminal P1. The output voltage at is relatively low.

  On the other hand, when there is no object in the detection gap G1, the light emitted from the light emitting diode 111 is received by the phototransistor 121 without being reflected by an obstacle, so the amount of light received by the phototransistor 121 is relatively large. As a result, the output voltage at terminal P1 is relatively high.

  A detection unit (not shown) is connected to the terminal P1 of the optical sensor 100, and in this detection unit, the output voltage value at the terminal P1 is compared with a preset threshold voltage value, thereby detecting a detection gap. The presence or absence of an object in G1 can be detected. That is, if the output voltage value is lower than the threshold voltage value, it can be detected that there is an object. On the other hand, if the output voltage value is not less than the threshold voltage value, it can be detected that there is no object.

  On the other hand, the optical sensor control device 200 includes a CPU 230, an SRAM 240, and a FEPROM 250, and each is connected to an internal bus 260. The optical sensor control device 200 includes an A / D conversion unit 210 and a light receiving sensitivity adjustment circuit 220.

  Among these, the SRAM 240 has an adjustment setting value storage unit 240a, and the FEPROM 250 has an operation setting value storage unit 250a. Further, the CPU 230 functions as the control unit 230a by executing a program for controlling the optical sensor 100 stored in the FEPROM 250.

  The A / D conversion unit 210 is connected to the light receiving unit 120 and the CPU 230 in the optical sensor 100. The A / D conversion unit 210 inputs the output voltage (analog) of the light receiving unit 120 and converts it into digital data (output voltage value). It outputs to CPU230. The light receiving sensitivity adjustment circuit 220 is connected to the light receiving unit 120 and the CPU 230 similarly to the A / D conversion unit 210.

  FIG. 2 is an explanatory diagram showing the light receiving sensitivity adjustment circuit 220 shown in FIG.

  The light receiving sensitivity adjustment circuit 220 illustrated in FIG. 2 includes ten resistors (R1 to R10) and transistors TR1 to TR10 connected in series to the resistors R1 to R10. The resistors R1 to R10 are connected in parallel to each other, and are connected to the light receiving unit 120 of the optical sensor 100 when the corresponding transistors TR1 to TR10 are turned on, respectively.

  The resistance values of the resistors R1 to R10 are the smallest in the resistor R1, and increase in the order of the resistor R1, the resistor R2, the resistor R3,.

  In the optical sensor control device 200, by selectively connecting any one of the resistors R1 to R10 in the light receiving sensitivity adjustment circuit 220 to the light receiving unit 120, the light receiving sensitivity in the light receiving unit 120 can be changed.

  In the phototransistor, as the connected resistance (load resistance) is larger, the phototransistor is turned on with a smaller amount of received light, so that the light receiving sensitivity is higher. Therefore, by selecting a resistor having a larger resistance value and connecting it to the light receiving unit 120, the light receiving sensitivity of the light receiving unit 120 can be further increased.

  Here, “operation setting value” is set as a value indicating the resistance connected to the light receiving unit 120, and 1, 2,..., R10 for the resistances R1, R2,. 10 is set. The operation setting value is stored in the operation setting value storage unit 250a. At the time of shipment of the optical sensor 100, “5” is set as an initial setting value.

  The control unit 230a described above corresponds to the reading unit and the adjustment unit in the claims, and the light receiving sensitivity adjustment circuit 220 described above corresponds to the load resistance in the claims.

  The optical sensor 100 and the optical sensor control device 200 described above can detect, for example, whether or not there is cash inserted in an automatic teller machine (ATM) or whether or not there is printing paper in a printer. It can be used for detecting the home position of the print head.

  Here, in the optical sensor 100, the light receiving sensitivity of the light receiving unit 120 may decrease due to deterioration over time. And the output voltage characteristic of the light-receiving part 120 also changes with the fall of this light-receiving sensitivity.

  FIG. 3 is an explanatory diagram illustrating an example of output voltage characteristics of the light receiving unit 120. In FIG. 3, the horizontal axis represents the amount of received light, and the vertical axis represents the output voltage value at the light receiving unit 120.

  In FIG. 3, a curve A represents the output voltage characteristic of the light receiving unit 120 before shipment of the optical sensor 100, and a curve B represents the output voltage characteristic of the light reception unit 120 after shipment of the optical sensor 100. The curves C, S, T, and X indicated by broken lines will be described later.

  In FIG. 3, the received light amount P is the received light amount when there is no object in the detection gap G1, and the received light amount Q is the received light amount when there is an object in the detection gap G1. Further, it is assumed that a threshold voltage value for determining the presence / absence of an object is set to 2 V in a detection unit (not shown).

  When the light receiving sensitivity of the light receiving unit 120 decreases due to deterioration with time, the output voltage value at the same received light amount becomes lower than before the light receiving sensitivity decreases. Therefore, as shown in FIG. 3, when the output voltage characteristic of the light receiving unit 120 before shipment is the curve A, the output voltage characteristic may change to the curve B due to deterioration with time of the light receiving unit 120 after shipment. Can happen.

  When the output voltage characteristic changes from the curve A to the curve B, as shown in FIG. 3, the output voltage value at the amount of received light P is 1.5V, which is lower than the threshold voltage value 2V. As a result, although there is no object in the detection gap G1, a detection unit (not shown) erroneously detects that there is an object.

  Therefore, the optical sensor control apparatus 200 performs light receiving sensitivity adjustment processing, which is a characteristic part of the present invention described later, so as not to cause such erroneous detection.

A2. Overview of light sensitivity adjustment processing:
An outline of the light receiving sensitivity adjustment process, which is a characteristic part of the present invention, will be described with reference to FIG.

  In the optical sensor control device 200, when the light receiving sensitivity of the light receiving unit 120 decreases and the output voltage characteristic changes from the curve A to the curve B shown in FIG. By changing, the light receiving sensitivity is adjusted to be increased.

  Here, in the optical sensor control device 200, the light receiving sensitivity is adjusted so that the adjusted output voltage characteristic falls within the range of the curve S to the curve T shown in FIG. In the curve S, the output voltage value at the amount of received light P is 2.5V, which is higher than the threshold voltage value (2V). Therefore, when the error (0.5 V) is taken into consideration, when the light receiving sensitivity of the light receiving unit 120 is lower than the light receiving sensitivity corresponding to the curve S, the output voltage value at the light receiving amount P is less than 2 V, which is not illustrated. The detection unit may erroneously detect that there is an object even though there is no object. Therefore, this curve S is set to a minimum level of appropriate output voltage characteristics.

  On the other hand, in the curve T, the output voltage value at the received light quantity Q is 1.5V, which is lower than the threshold voltage (2V). Therefore, in consideration of a slight error (0.5 V), when the light receiving sensitivity of the light receiving unit 120 is higher than the light receiving sensitivity corresponding to the curve T, the output voltage at the light receiving amount Q exceeds 2 V, and is not shown. There is a risk that the detecting unit that is not present will erroneously detect that there is no object despite the presence of the object. Therefore, this curve T is set to the highest level of appropriate output voltage characteristics.

  Whether or not the output voltage characteristic is within the range from the curve S to the curve T as a result of adjusting the light reception sensitivity is determined by the output voltage value at the light reception amount P. That is, since the output voltage value at the light reception amount P in the curve S is 2.5V and the output voltage value at the light reception amount P in the curve T is 3.8V, the output voltage value at the light reception amount P is 2.V. The light receiving sensitivity is adjusted so as to be within the range of 5V to 3.8V.

  Here, the light receiving unit 120 receives the light reception amount P under the condition that there is no object in the detection gap G1 as described above. Such a condition corresponds to the “predetermined condition that maximizes the amount of light emitted from the light emitting unit at the light receiving unit” in the claims.

  The voltage range of 2.5 V to 3.8 V described above corresponds to the “predetermined ideal output voltage value range” in the claims, and 3.8 V and 2.5 V are the upper limit value and the lower limit value, respectively. Corresponds to the value.

A3. Details of light sensitivity adjustment processing:
As a premise of the light receiving sensitivity adjustment process that is a characteristic part of the present invention, the operation setting value storage unit 250a shown in FIG. 1 stores the operation setting value “5”, and the transistor TR5 shown in FIG. 2 is turned on. The resistor R5 is connected to the light receiving unit 120. The output voltage characteristic of the light receiving unit 120 before shipment is assumed to be a curve A shown in FIG. Then, it is assumed that the light receiving sensitivity of the light receiving unit 120 decreases due to deterioration with time, and the output voltage characteristic changes from the curve A to the curve B. In the light emitting unit 110, it is assumed that the luminance of the light emitting diode 111 does not decrease.

  Here, as shown in FIG. 3, the output voltage value at the received light amount P (the received light amount when there is no object in the detection gap G1) in the curve B is 1.5V. In addition, it is assumed that 2 V is set as the threshold voltage value in a detection unit (not shown). Therefore, as described above, a detection unit (not shown) erroneously detects that there is an object even though there is no object in the detection gap G1, as described above.

  The optical sensor 100 and the optical sensor control device 200 can be turned off / on by the user.

  Under the above premise, when the power of the optical sensor 100 and the optical sensor control device 200 is turned on by the user, the light sensor sensitivity adjustment processing is executed in the optical sensor control device 200. At this time, it is assumed that there is no object in the detection gap G1.

  FIG. 4 is a flowchart showing the procedure of light receiving sensitivity adjustment processing in the present embodiment.

  When the light receiving sensitivity adjustment process shown in FIG. 4 is started, the control unit 230a shown in FIG. 1 uses the operation setting value stored in the operation setting value storage unit 250a as the adjustment setting value in the adjustment setting value storage unit 240a. Store (step S302).

  The adjustment set value is a value indicating a resistance connected to the light receiving unit 120 in the light receiving sensitivity adjustment processing. As described above, when “5” is stored as the operation setting value, “5” is stored in the adjustment setting value storage unit 240a as the adjustment setting value.

  Next, the control unit 230a reads the output voltage value input via the A / D conversion unit 210 (step S304) and determines whether the output voltage value is lower than 2.5V (step S306). .

  As described above, when the output voltage value when there is no object in the detection gap G1 is 1.5V, the control unit 230a reads the output voltage value (1.5V). It will be determined that the voltage is lower than 2.5V.

  When the output voltage value is determined to be lower than 2.5 V as described above, the control unit 230a reads out the adjustment setting value from the adjustment setting value storage unit 240a, and the adjustment setting value is the maximum value “10”. It is determined whether or not there is (step S308). As described above, when “5” is stored as the adjustment setting value, the control unit 230a determines that the adjustment value is not the maximum value “10”.

  If it is determined that the adjustment setting value is not the maximum value “10”, the control unit 230a stores the adjustment setting value that is one level higher in the adjustment setting value storage unit 240a instead of the current adjustment setting value (Step S230). S310). As described above, when the current adjustment setting value is “5”, “6” is stored in the adjustment setting value storage unit 240a as a new adjustment setting value.

  Next, the control unit 230a reads the adjustment set value from the adjustment set value storage unit 240a, and turns on the transistor corresponding to the set adjustment value (step S312).

  As described above, since “6” is newly stored in the adjustment setting value storage unit 240a as the adjustment setting value, the control unit 230a turns on the transistor TR6. In this case, the resistor R6 is connected to the light receiving unit 120. As described above, since the resistance value of the resistor R6 is larger than that of the resistor R5, the light receiving sensitivity of the light receiving unit 120 is higher than that when the resistor R5 is connected. As a result, the output voltage characteristic changes and the output voltage value becomes higher.

  And after performing the process of step S312, it returns to step S306 again. And until it determines with an output voltage value not being lower than 2.5V in step S306, the control part 230a repeats the process of step S306-step S312.

  By repeating the processing from step S306 to step S312, the adjustment setting value increases one by one. Accordingly, a resistor having a larger resistance value is connected to the light receiving unit 120, and the output voltage value becomes higher.

  As a result of repeating the processing of step S306 to step S312, when the adjustment set value is “8” and the resistor R8 is connected to the light receiving unit 120, the output voltage characteristic becomes the curve A shown in FIG. Assume that the output voltage value at P has increased to 2.8V.

  In this case, the control unit 230a determines that the output voltage value is not lower than 2.5V in the process of step S306, and then determines whether the output voltage value is higher than 3.8V. (Step S314). As described above, when the output voltage value rises to 2.8V, the output voltage value is lower than 3.8V, so the control unit 230a determines that the output voltage value is not higher than 3.8V.

  When the control unit 230a determines that the output voltage value is not higher than 3.8V, the control unit 230a reads the adjustment setting value from the adjustment setting value storage unit 240a, and uses the adjustment setting value as an operation setting value. 250a is stored (step S316), and the light receiving sensitivity adjustment process is terminated.

  As a result of the above light receiving sensitivity adjustment processing, “8” is stored as the operation setting value in the operation setting value storage unit 250a. And since the output voltage value in the light reception amount P changes to 2.8V, it becomes higher than a threshold voltage value (2V), and the false detection of the detection part which is not shown in figure can be suppressed.

  In the process of step S308, if the adjustment resistance value is the maximum value “10”, the light receiving sensitivity cannot be further increased. Therefore, in the process of step S316, “10” is set as the operation setting value. Then, the light receiving sensitivity adjustment process is completed.

  The above is a case where the light receiving sensitivity of the light receiving unit 120 is lowered due to deterioration over time. However, due to manufacturing variations, the light receiving sensitivity of the light receiving unit 120 is relatively low before shipment, and the output voltage characteristics are shown in FIG. Even in the case of the curve B, erroneous detection of a detection unit (not shown) can be suppressed by performing the above-described light receiving sensitivity adjustment processing after shipment.

  Hereinafter, a case will be described in which the light receiving sensitivity of the light receiving unit 120 is relatively high and the output voltage characteristics are a curve C shown in FIG. 3 due to manufacturing variations.

  As shown in FIG. 3, in curve C, the output voltage value at the received light amount P is 4V, and the output voltage value at the received light amount Q is 2.1V. In addition, it is assumed that 2V is set in the detection unit (not shown) as in the case where the light receiving sensitivity is reduced. Therefore, as described above, the detection unit (not shown) erroneously detects that there is no object even though there is an object in the detection gap G1, as described above.

  Also in this case, erroneous detection can be suppressed by executing the above-described light receiving sensitivity adjustment processing. In addition, as the premise of the light receiving sensitivity adjustment process described below, the output voltage characteristic of the light receiving unit 120 is the curve C shown in FIG. 3 and the light receiving unit 120 is not deteriorated with time. Since this is the same as the case where the light receiving sensitivity of the light receiving unit 120 is lowered, the description thereof is omitted.

  Under the above premise, when the power of the optical sensor 100 and the optical sensor control device 200 is turned on by the user, the light receiving sensitivity adjustment process is started. And after the process of step S302 and step S304 mentioned above is performed, in the process of step S306, the control part 230a will determine with an output voltage not being lower than 2.5V. Therefore, the control unit 230a determines whether or not the output voltage is higher than 3.8V (step S314).

  Since the output voltage value at the amount of received light P is 4V as described above, the control unit 230a determines that the output voltage value is higher than 3V, unlike the case where the light receiving sensitivity of the light receiving unit 120 is reduced. It becomes. Thus, in the process of step S314, when it is determined that the output voltage value is higher than 3V, the control unit 230a reads the adjustment setting value from the adjustment setting value storage unit 240a, and the adjustment setting value is the lowest value “1”. ] Is determined (step S318).

  As described above, when “5” is stored as the adjustment setting value, the control unit 230a determines that the adjustment value is not the minimum value “1”. If it is determined that the adjustment setting value is not the minimum value “1”, the control unit 230a stores the next adjustment setting value in the adjustment setting value storage unit 240a instead of the current adjustment setting value (step S110). S320). As described above, when the current adjustment setting value is “5”, “4” is stored in the adjustment setting value storage unit 240a as a new adjustment setting value.

  Next, the control unit 230a reads the adjustment set value from the adjustment set value storage unit 240a, and turns on the transistor corresponding to the set adjustment value (step S322).

  As described above, since “4” is newly stored in the adjustment setting value storage unit 240a as the adjustment setting value, the control unit 230a turns on the transistor TR4. In this case, the resistor R4 is connected to the light receiving unit 120. As described above, since the resistance value of the resistor R4 is smaller than that of the resistor R5, the light receiving sensitivity of the light receiving unit 120 is lower than that when the resistor R5 is connected. As a result, the output voltage characteristic changes and the output voltage value becomes lower.

  And after performing the process of step S322, it returns to step S314 again. And until it determines with the output voltage value not being higher than 3.8V in the process of step S314, the control part 230a repeats the process of step S314 and step S318-step S322.

  By repeating the processing of step S314, step S318 to step S322, the adjustment set value is lowered one by one. Accordingly, a resistor having a smaller resistance value is connected to the light receiving unit 120, and the output voltage The value will be lower.

  As a result of repeating the processes of steps S314 and S318 to S322, the adjustment set value is “3”, and the output voltage value is less than 3.8 V when the resistor R3 is connected to the light receiving unit 120. And In this case, the process of step S316 described above is executed, "3" is stored as the operation setting value in the operation setting value storage unit 250a, and the light receiving sensitivity adjustment process is completed.

  As a result of the light receiving sensitivity adjustment process described above, “3” is stored as the operation setting value in the operation setting value storage unit 250a. In this case, the output voltage value at the amount of received light Q is lower than the threshold voltage value (2 V), so that erroneous detection of a detection unit (not shown) can be suppressed.

  In the process of step S318, if the adjustment resistance value is the lowest value “1”, the light receiving sensitivity cannot be lowered any more. Therefore, in the process of step S316, “1” is set as the operation setting value. Then, the light receiving sensitivity adjustment process is completed.

A4. Effects of the embodiment:
As described above, in the optical sensor control device 200, the control unit 230a reads the output voltage value in the light receiving unit 120, and when the output voltage value is higher than 2.5V, the output voltage value is 2.5V-3. A resistor having a larger resistance value is connected to the light receiving unit 120 until it is in the range of .8V. As a result, the light receiving sensitivity can be increased, and the output voltage value when there is no object in the detection gap G1 can be made higher than 2V.

  Therefore, when the light receiving sensitivity of the light receiving unit 120 decreases due to deterioration with time, or when the light receiving sensitivity of the light receiving unit 120 is relatively low from the beginning of shipping due to manufacturing variations, the object remains in spite of the absence of the object in the detection gap G1. It is possible to suppress false detection by a simple method.

  On the other hand, when the read output voltage value is higher than 3.8V, the control unit 230a provides a resistor having a smaller resistance value until the output voltage value is in the range of 2.5V to 3.8V. To connect to. As a result, the light receiving sensitivity can be reduced, and the output voltage value when an object is present in the detection gap G1 can be made lower than 2V.

  Therefore, in the case where the light receiving sensitivity of the light receiving unit 120 is relatively high from the beginning of shipping due to manufacturing variation, it is possible to suppress erroneous detection that there is no object despite the presence of the object in the detection gap G1 by a simple method. Can do.

  In addition, by performing the light reception sensitivity adjustment process described above, the luminance of the light emitting diode 111 is relatively low from the beginning of shipment due to the deterioration of the light emitting unit 110 due to aging or due to manufacturing variations (or Even in the case of relatively high), erroneous detection can be suppressed by a simple method.

  For example, when the luminance of the light emitting diode 111 is reduced as compared to before shipment due to deterioration with time, the amount of light received by the light receiving unit 120 is reduced. In this case, assuming that the light receiving sensitivity of the light receiving unit 120 has not changed, the output voltage value at the same received light amount is lower than before shipment. As a result, if the output voltage value when there is no object in the detection gap G1 falls below the threshold voltage value, it is erroneously detected that there is an object.

  Therefore, by performing the light reception sensitivity adjustment process described above, the light reception sensitivity of the light receiving unit 120 is increased, and the output voltage value when there is no object in the detection gap G1 can be made to exceed the threshold voltage value. Such erroneous detection can be suppressed by a simple method.

  Here, instead of the light receiving sensitivity adjustment process described above, a method of suppressing false detection by changing the threshold voltage value according to the output voltage value in a detection unit (not shown) is also conceivable.

  For example, when the light receiving sensitivity of the light receiving unit 120 decreases and the output voltage characteristic of the light receiving unit 120 changes from the curve A to the curve B shown in FIG. 3, as described above, there is no object in the detection gap G1. The output voltage value will drop from 2.5V to 1.5V. In this case, for example, in a detection unit (not shown), the threshold voltage value is reduced from 2 V to 1 V, thereby suppressing erroneous detection that there is an object even though there is no object in the detection gap G1. be able to.

  In contrast to this method, the present invention has the following advantageous effects.

  Consider a case where the light receiving sensitivity of the light receiving unit 120 is lowered and the output voltage characteristic changes from the curve A shown in FIG. 3 to the curve X shown by a broken line. In this case, as shown in FIG. 3, the output voltage value at the received light amount P and the output voltage value at the received light amount Q are approximately the same at the voltage value α.

  Therefore, by setting the threshold voltage value to a value lower than the voltage value α by changing the threshold voltage value, it is erroneously detected that there is an object even though there is no object in the detection gap G1. That can be suppressed. However, when there is an object in the detection gap G1 (in the case of the amount of received light Q), the output voltage value (voltage value α) is higher than the threshold voltage value. It will be erroneously detected.

  On the other hand, if the threshold voltage value is set to a value higher than the voltage value α, the output voltage value (voltage value α) becomes lower than the threshold voltage value when there is no object in the detection gap G1, so that it is not shown. The detection unit will erroneously detect that there is an object.

  On the other hand, in the present invention, when the light receiving sensitivity of the light receiving unit 120 decreases and the output voltage characteristic changes from the curve A to the curve X, the light receiving unit 120 is subjected to the light receiving sensitivity adjustment process described above. Is increased so that the output voltage characteristic of the light receiving unit 120 falls within the range from the curve S to the curve T, so that such erroneous detection can be suppressed.

B. Variation:
The present invention is not limited to the above-described examples and embodiments, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are possible. .

B1. Modification 1:
In the light reception sensitivity adjustment process in the above-described embodiment, when the control unit 230a determines that the adjustment setting value is the maximum value “10” in the process of step S308, the control unit 230a operates the maximum value “10” in the process of step S316. Although it has been stored as a set value and the light reception sensitivity adjustment processing has been completed, the present invention is not limited to this.

  If it is determined in step S308 that the maximum value is “10”, the output voltage value at the received light amount P is smaller than 2.5V even though the light receiving sensitivity of the light receiving unit 120 is in the highest state. State. Therefore, even if the light receiving sensitivity is adjusted further, it is impossible to suppress erroneous detection. Therefore, instead of the processing in step S316 described above, guidance for prompting replacement of the optical sensor may be displayed on a display unit (not shown) such as a liquid crystal panel connected to the optical sensor control device 200.

  It should be noted that similar processing may be performed when it is determined in step S318 that the adjustment setting value is the minimum value “1”.

B2. Modification 2:
In the embodiment described above, the optical sensor control device 200 is configured to convert the output voltage (analog) of the light receiving unit 120 into digital data by the A / D conversion unit 210, but the present invention is limited to this. It is not a thing. The CPU 230 may include an A / D conversion circuit, and the A / D conversion circuit may convert the output voltage into digital data instead of the A / D conversion unit 210.

B3. Modification 3:
In the above-described embodiment, the light reception sensitivity adjustment processing is executed when the user turns on the power of the optical sensor 100 and the optical sensor control device 200. , Every day, etc.). By doing in this way, false detection can be suppressed by a simpler method.

B4. Modification 4:
In the embodiment described above, the optical sensor 100 is a transmissive photo interrupter, but may be a reflective photo interrupter. Even if the optical sensor is a reflection-side interrupter, by applying the present invention, the light-receiving sensitivity of the light-receiving unit or the luminance of the light-emitting unit changes due to deterioration over time, or the light-receiving unit due to manufacturing variations. In the case where there is a variation in the light receiving sensitivity and the luminance of the light emitting unit, it is possible to suppress erroneous detection of the presence or absence of an object.

  When the optical sensor 100 is a reflection type photo interrupter, there is an object that does not transmit light at the object detection position, and light emitted from the light emitting unit is reflected by the object and received by the light receiving unit. Under such conditions, the amount of received light is maximized. Therefore, such a condition corresponds to “a predetermined condition in which the amount of light emitted from the light emitting unit at the light receiving unit is maximized” in the claims.

B5. Modification 5:
In the above-described embodiment, the light receiving sensitivity adjustment circuit 220 is configured to include the ten resistors R1 to R10, but can be connected to the phototransistor 121 as a load resistor, and the resistance value can be changed. The configuration is not limited to the number of resistors. For example, a configuration including one variable resistor may be used.

B6. Modification 6:
In the above-described embodiment, each part of the optical sensor control device 200 may be configured by hardware instead of software, or may be configured by hardware. You may do it. For example, the above-described control unit 230a may be configured by hardware.

It is explanatory drawing which shows schematic structure of the optical sensor and optical sensor control apparatus as one Example of this invention. It is explanatory drawing which shows the light reception sensitivity adjustment circuit 220 shown in FIG. 6 is an explanatory diagram illustrating an example of output voltage characteristics of a light receiving unit 120. FIG. It is a flowchart which shows the procedure of the light reception sensitivity adjustment process in a present Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Optical sensor 110 ... Light emission part 111 ... Light emitting diode 120 ... Light receiving part 121 ... Phototransistor 200 ... Optical sensor control apparatus 220 ... Light reception sensitivity adjustment circuit 230 ... CPU
230a ... Control unit 240 ... SRAM
240a ... Adjustment setting value storage unit 250 ... FEPROM
250a ... Operation set value storage 260 ... Internal bus P1 ... Terminal G1 ... Detection gap TR1-TR10 ... Transistor R1-R10 ... Resistance

Claims (5)

An optical sensor control device for controlling an optical sensor for detecting the presence or absence of a detection object having a light emitting unit and a light receiving unit that outputs a voltage according to the amount of received light,
A reading unit that reads an output voltage value of a voltage output from the light receiving unit;
An adjustment unit capable of adjusting the light receiving sensitivity of the light receiving unit;
With
The reading unit has a predetermined condition in which a light receiving amount of the light emitted from the light emitting unit is maximized at a detection position determined by an installation position of the light emitting unit and an installation position of the light receiving unit. Then, read the output voltage value,
The adjustment unit adjusts the light receiving sensitivity based on a read output voltage value read by the reading unit under the predetermined condition. The optical sensor control device according to claim 1,
The adjusting unit compares the read output voltage value with an upper limit value and a lower limit value of a preset ideal output voltage value range,
The adjustment unit decreases the light receiving sensitivity when the reading output voltage value is higher than the upper limit value, and increases the light receiving sensitivity when the reading output voltage value is lower than the lower limit value.
Optical sensor control device. The optical sensor control device according to claim 2,
The light receiving unit includes a phototransistor,
The adjustment unit has a load resistance connected to the phototransistor,
When the read output voltage value is higher than the upper limit value, the adjustment unit changes the resistance value of the load resistance to a smaller value, and when the read output voltage value is lower than the lower limit value, Change the resistance value of the load resistance to a larger value,
Optical sensor control device. The optical sensor control device according to any one of claims 1 to 3,
The optical sensor is a transmissive photo interrupter,
The predetermined condition is a condition that there is no object to be detected in a gap between the light emitting unit and the light receiving unit.
Optical sensor control device. An optical sensor control method for controlling an optical sensor for detecting the presence or absence of a detection object having a light emitting unit and a light receiving unit that outputs a voltage according to the amount of received light,
At a detection position determined by the installation position of the light emitting unit and the installation position of the light receiving unit, the light receiving unit is subjected to a predetermined condition that maximizes the amount of light emitted from the light emitting unit at the light receiving unit. A first step of reading an output voltage value of a voltage output from
A second step of adjusting the light receiving sensitivity of the light receiving unit based on the output voltage value read under the predetermined condition;
An optical sensor control method comprising:

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